In recent years, changes in lifestyle leads to wide use of electronic devices, such as notebook computers, tablet computers, smartphones, e-books, personal digital assistants (PDA), and multimedia players.
The aforesaid electronic devices are powered by batteries. Hence, what is important to the aforesaid electronic devices is the data related to battery power level and battery sustainability.
According to the prior art, engineers enable an electronic device to operate for a longer period of time before its battery runs out of power, by taking the following measures: increasing the battery capacity, making the electronic device more power-saving, or providing an additional auxiliary power source to the electronic device.
Electronic devices can be rendered power-saving through power management. The most power-consuming component of a display-enabled electronic device is a display screen. Take a liquid crystal display screen as an example, the liquid crystal display screen comprises liquid crystal cells and a backlight unit. The backlight unit generates light for lighting up the liquid crystal cells in operation. If the liquid crystal cells in operation are not lit up, users cannot read what is displayed on the liquid crystal cells. In general, the backlight unit is the most power-consuming components of a display-enabled electronic device.
Known ways of power management of a display-enabled electronic device are of two categories, namely hardware-based power management and software-based power management. The hardware-based power management involves detecting ambient light with a light sensor (such as a photoresistor), increasing the light intensity of the light generated from the backlight unit when strong light intensity of ambient light is detected to allow the user to read an image displayed on the liquid crystal cells, and decreasing the light intensity of the light generated from the backlight unit when weak light intensity of ambient light is detected to save power.
Furthermore, take a smartphone as an example, the speaker is equipped with a light sensor whereby the backlight unit is shut down as soon as the user starts a conversation on the smartphone. The software-based power management involves detecting the use status of the electronic device and instructing the electronic device to enter a standby mode, a hibernation mode, or a shutdown mode upon detection that the electronic device is idle.
However, the aforesaid prior art has its own drawbacks. First, the additional hardware (such as a light sensor) also consumes power to the detriment of power saving. Second, although the software-based power management saves power by determining the point in time to start or shut down the backlight unit, it does not offer a power-saving solution to the backlight unit in operation.